The piss stream have ended leaving the distinct tangy piss flavor in your mouth. Your mouth still engulfs the perimiter of sisters pussy. She shifts her weight a bit and pushes the outside of your throat with her hand. You are not sure what this is supposed to mean, so you remain motionless.
Doing nothing was apparantly not the correct move, this time she hits your thorat while mumbling, "Stupid piece of shit bidet".
You get the hint that she wants to be cleaned and figures some manual work from your side needs to happen. You extend your tongue and start by exporing her skin outside of her vulva and working your way inwards. She appears pleased with your actions as she gently leans forward and looks at her phone. Tasting the sweat and sex of your sister was not something you thought that you would do. But being a toilet now this was something you had to get used to.
After a minute of putting your tongue inside the folds of your sisters pussy she stands up showing her rear in all it's glory, but alas, she pulls up her pants and leaves the room. She didn't close my mouth, you think still feeling her toenails and piss still inside of you.
Still dazed by the ordeal something else happens.